So when I am using images other than my own as references there is a nagging question.
The law is that copyright remains with the creator of the image unless you have an instruction from the creator saying otherwise.
Using the image as reference means I will no doubt recreate elements but how much is necessary so as not to infringe on copyright? How derivative must the image be ?
This has proven to be a difficult question to answer. The famous case of Rogers v Koons demonstrates some of the key elements of infringement. A really interesting commentary on the case is included on the American Society of Portrait Artist Site.